Noise may include random fluctuations in electrical signals. The noise may be errors or undesired random disturbances of a useful information signal. The noise is a summation of unwanted or disturbing energy from natural or man-made sources. Noise may be quantified by a signal-to-noise ratio (SNR). Noise may have various sources. Noise may include, for example, thermal noise, shot noise, flicker noise, burst noise, transit-time noise, coupled noise, intermodulation noise, crosstalk, interference, or industrial noise. Industrial noise may include noise from the components of equipment, which may affect surrounding components or components within the equipment. For example, noise may be generated when an electric motor starts and stops. In another example, water on a touch-panel may cause a variance in capacitance and thus introduce noise.
Noise may be reduced through a variety of techniques. Noise can be reduced through Faraday cages, avoiding capacitive coupling, or avoiding ground loops. However, in some cases it is not possible to have all ground connections connected to an identical ground bus.
Noise may be typically measured as an electrical power N in watts or dBm, a root mean square (RMS) voltage (identical to the noise standard deviation) in volts, dBμV or a mean squared error (MSE) in volts squared. Noise may also be characterized by its probability distribution and noise spectral density in watts per hertz. A noise signal is typically considered as a linear addition to a useful information signal. Noise power can be measured in watts or decibels (dB) relative to a standard power.